Tuff

Llechau-uchaf is formed from the late Cambrian 'Lingula Flags' whilst Carreg-trai is formed from Ordovician acid tuffs of the Llanrian Volcanic Formation.

The thick, white-hot ash spewed forth from the nearby Turkey Creek Caldera, cooled and hardened into rhyolitic tuff, laying down almost 2,000 ft (610 m) of highly siliceous, dark volcanic ash and pumice.

The site is dominated by volcanic tuff, limestone, and silica deposits of large freshwater lakes associated with hot springs and local basaltic (high-iron) volcanism.

the Heritage Group is the Union Glacier Formation of ashflow tuff-lahar deposits, the Hyde Glacier Formation of graywacke-argillite-conglomerate, the Drake Icefall Formation of black shales and marble, the Conglomerate Ridge

The space between the two islets is the old volcanic crater formed of tuff rock and is approximately 20 metres (66 ft) deep.

Pitcairn Island is a volcanic remnant primarily formed of tuff, where the north side of the cone has been eroded.

Notable examples of potreros include some of the many mesas of the Pajarito Plateau near Santa Fe, New Mexico (United States).These "finger mesas" were once a continuous deposit of compressed volcanic ash (the Bandelier Tuff).

The Tunkin volcanic field has filled the Tunkin Depression with about 500 metres (1,600 ft) of volcanic products, which range from Miocene to Quaternary and include basaltic lava flows and tuffs.

Tuff